The requirement of fast data transmission and highly dense wirings between the computer and the peripheral device becomes more and more desired nowadays. Meanwhile, general-purpose USB is generally used to connect between a computer and a peripheral device.
A conventional USB cable (with standards USB 2.0 and 3.0) employs an electrical cable to connect and transmit signal (hereinafter, referred to as “electrical USB cable”). Traditionally, the electrical USB cables are formed by twisted pair to reduce the electromagnetic interference (EMI) from environmental noise sources and also the crosstalk between adjacent pairs. However, twist pair would have different wire lengths and hence introduce difference signaling delay to the differential signal; as a result, it will increase jitter and hence reduce the signal quality and transmission bandwidth. Moreover, the transmission length is also limited due to the signal attenuation.
As an alternative to the electrical USB cable, an optical USB cable in which an optical signal is transmitted using optical waveguides has recently been proposed. In the optical USB cable, for example, optical connections rather than electrical connections are used as buses for connecting between a computer and a peripheral device.
Although such optical USB cable can obtain a higher transmission data and a longer transmission distance than that of the electrical USB cable, the energy issue becomes serious. For ensuring the fast data transmission, the conventional optical USB cable is always under a high speed status, no matter it is in the idle status. Thus, the power consumption is quite high, and the energy is wasted, which goes against the actual demand nowadays.
Hence, it is desired to provide an improved optical communication module and a universal serial bus cable to overcome the above-mentioned drawbacks.